The present closure is of the type which is known as a clam-shell locking apparatus. It is adapted as a portable lock closure to removably engage the external doorknob of a room which is to be secured as a second locking alternative, for example on a motel or hotel door. Its further utility serving as a supplemental lock for the domicile. After the device has been set, one may open the door from the inside for exit. The specific function of the device is to prevent others, who may have a key or passkey to doorknob of the room or home, from entering and it serves also as an extra lock on one door at night.
The portable closure device comprises upper and lower shell segments, the latter being hinged to the former for drop-away release and subsequent closure upon the doorknob. The lower segment retains a latch cam which is adapted to operatively engage a spring-loaded latch upon closure. The latch of the upper segment incorporates a latch and lever combination which may be opened by an appropriate key lock or the like. Among advantages achieved through the use of the device are the following. The door lock closure handily slips over a given doorknob and its compartments close around it; moreover, after closure it will swing 360 degrees on the doorknob, thereby making it impossible for an intruder to turn the knob. It is useful to protect either an ordinary door knob or one which contains its own axial key lock.
______________________________________ THE PRIOR ART INVENTOR YEAR PAT. NO. TITLE ______________________________________ Kaskouras 1949 2,458,002 DOOR KNOB LOCK De Forrest 1966 3,245,240 KNOB PROTECTOR Marcy 1983 4,391,111 LATCHING MECH- ANISM FOR DISPENSER APPARATUS Johnson 1986 4,631,938 ACCESSORY KEY- HOLD LOCK De Forrest, Sr. 1989 4,798,069 PROTECTING DE- VICE FOR LEVER HANDLE DOOR LOCKS Johnson 1989 4,838,059 COMBINED COVER AND ATTACHING MEANS FOR CON- CEALING A DEAD- BOLT LOCK Johnson 1991 5,033,280 SECURITY LOCK Zaucha 1991 5,079,935 TRAPPED KEY LOCK ______________________________________